Technically:
- Users. If you register an account to purchase, download, or play games or other content from itch.io, you agree to be bound to the terms of this Agreement as a platform user (“User”). Users affirm that they are over the age of 13, as the Service is not intended for children under 13.
BUT... for publishing, technically you're right, but look at the bold text:
- Publishers. If you register an account to sell, distribute, or publish games or other content on itch.io, you agree to be bound to the terms of this Agreement as a platform publisher (“Publisher”). Publishers affirm that they are either more than 18 years of age, or possess legal parental or guardian consent, and are fully able and competent to enter into the terms, conditions, obligations, affirmations, representations and warranties set forth in this Agreement.
So yeah, 10 and 11 are problematic, but 13+ is perfectly acceptable as long as they have permission.